We are investigating the psychobiology of cognition in man. We attempt to interrelate psychological and biological determinants of various components of cognition, such as the specific and discrete psychobiological mechanisms that define the acquisition, processing, encoding, consolidation, and retrieval of experience. Experiments are designed to examine the biological and psychological determinants of psychiatric and neuropsychiatric alterations in cognitive processes in adults and children. Specific forms of central nervous system dysfunctions (e.g., as defined by type of lesion in neuropsychiatric disorders) may affect specific and distinct components of cognitive processing. Similarly, psychoactive drugs that affect discrete aggregrates of neurons may affect discrete aspects of cognition and information processing. Based on empirical studies of clinical populations (e.g., depression, Alzheimer's disease, Korsakoff's disease, forms of learning impairments in children) and on several types of psychoactive agents (cholinergic drugs, noradrenergic drugs, neuropeptides), it has been possible to begin to describe the psychobiological relationships between semantic and episodic memory, encoding processes, and effortful (active) cognitive operations as opposed to automatic cognitive processes.